Casein interaction with lipid membranes: Are the phase state or charge density of the phospholipids affecting protein adsorption?

• Published in: Biochimica et biophysica acta. Biomembranes Vol. 1860; no. 12; pp. 2588 - 2598
• Main Authors: Crespo-Villanueva, Adrián, Gumí-Audenis, Berta, Sanz, Fausto, Artzner, Franck, Mériadec, Cristelle, Rousseau, Florence, Lopez, Christelle, Giannotti, Marina I., Guyomarc'h, Fanny
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2018; Elsevier
• Subjects: Atomic force microscopy; Casein proteins; Food and Nutrition; Food engineering; Life Sciences; Phospholipid membrane; Physics; Supported lipid bilayer; Atomic force microscopy; Casein proteins; Phospholipid membrane; Supported lipid bilayer; protéine du lait; caséine; diffraction x; phospholipide; micelle de caséine; microscopie à force atomique; xrd; phospholipid; cellule mammaire; membrane de phospholipide; milk protein; membrane lipidique
• ISSN: 0005-2736; 1879-2642
• DOI: 10.1016/j.bbamem.2018.09.016

Casein micelles are ~200 nm electronegative particles that constitute 80 wt% of the milk proteins. During synthesis in the lactating mammary cells, caseins are thought to interact in the form of ~20 nm assemblies, directly with the biological membranes of the endoplasmic reticulum and/or the Golgi apparatus. However, conditions that drive this interaction are not yet known. Atomic force microscopy imaging and force spectroscopy were used to directly observe the adsorption of casein particles on supported phospholipid bilayers with controlled compositions to vary their phase state and surface charge density, as verified by X-ray diffraction and zetametry. At pH 6.7, the casein particles adsorbed onto bilayer phases with zwitterionic and liquid-disordered phospholipid molecules, but not on phases with anionic or ordered phospholipids. Furthermore, the presence of adsorbed caseins altered the stability of the yet exposed bilayer. Considering their respective compositions and symmetry/asymmetry, these results cast light on the possible interactions of casein assemblies with the organelles' membranes of the lactating mammary cells. [Display omitted] •Negatively charged 20-nm casein particles interact with membranes on milk synthesis.•Adsorption of individual casein particles onto lipid bilayers is observed using AFM.•Casein particles do not adsorb onto densely packed phospholipids in ordered phase.•Casein particles do not adsorb onto anionic phospholipids, even in disordered phase.•Casein particles adsorb onto zwitterionic and disordered phospholipid phase.